1. Field of the Invention
The present invention relates to an apparatus for continuously forcing an elongate raw material into an extrusion pressure vessel, wherein the raw material is a wire or rod of a metal such as aluminum which has to be extruded from the vessel in a continuous manner.
2. Related Art
For example in the case of extruding an aluminum material, it has been a common practice to repeat batch-wise steps, and in each step an aluminum billet is loaded in a container as the pressure vessel so as to be pressed through a die by a stem or ram which in turn is driven forward.
However in such a batch-wise system, the repeated loading of the billets has been lowering the productivity of this process, and in some of the thus extruded products a discontinuity has occurred due to the transfer from the preceding billet to the succeeding one. The discontinuity has not only impaired the quality, but also caused a lower yield of said products in a case wherein the discontinuous portions were eliminated.
The present inventor has therefore proposed a continuous extrusion system in which an elongate and extrusile aluminum raw material such as a wire or rod is continuously fed to a pressure vessel. The raw material is compressed in the vessel so as to be extruded through a die. Such a hew system will be exemplified below in the preferred embodiments of the present invention.
In the continuous extrusion system which was proposed by me, the extrusion pressure of the raw material is raised by the forcing thereof into the pressure vessel. Depending on the desired cross-sectional shape, the extrusion ratio, the nature and/or temperature of said raw material, it has been possible that an extraordinarily high pressure must be imparted to the material which is being loaded. For example, it has sometimes been difficult for a pair of simple drive rollers to grip and forcibly push the material into the pressure vessel.